Effect of temperature on short chain fatty acids (SGFAs) accumulation and microbiological transformation in sludge alkaline fermentation with Ca(OH)_2 adjustment

摘要

The effects of temperatures (15-55 ℃) on the alkaline fermentation of sewage sludge were investigated in semi-continuous stirred tank reactors (semi - CSTR) at the pH of 10. The highest soluble chemical oxygen demand (SCOD) yield was obtained at 55 ℃ (764.2 mg/ (gVS L d)), while the highest short chain fatty acids (SCFAs) yield was observed at 35 ℃ (319.8 mg/(gVS L d)), 1.5 times higher than SCFAs yield at 55 ℃ (209.5 mg/(gVS L d)). The proportion of the intercellular organic substances being transferred to the slime layer of sludge flocs increased from 29% at 15 ℃ to 54% at 55 ℃. But only a small part of soluble organic substances in the slime layers was converted to SCFAs at 55 ℃. The dewaterability of sludge was better at 35 ℃ than that at 55 ℃. Microbiological community analysis showed the acid-producing microorganisms at the medium temperatures (25 ℃ and 35 ℃) were more diverse and abundant than those at the low (15 ℃) and high temperatures (55 ℃). Clodtridium and Bacillus in Firmicutes and Gamma proteobacterium in Proteobacteria were the dominant functional bacterial species for high SCFA accumulation.